1. Field of the Invention
The present invention relates to a construction machine having a cooling fan, a radiator, and an oil cooler etc.
2. Description of the Related Art
Generally, a swiveling type construction machine such as a hydraulic excavator is known as a construction machine. This hydraulic excavator is made up of a lower traveling body capable of self-propulsion, and an upper swiveling body mounted upon the undercarriage. A working unit capable of moving up and down for carrying out land excavation etc. is provided on the front of the upper swiveling body.
The upper swiveling body comprises a swiveling frame forming the structure body, an engine mounted on the swiveling frame, a hydraulic pump driven by the engine, a hydraulic oil tank for storing hydraulic oil mounted on the swiveling frame, heat exchangers such as a radiator for cooling engine coolant and an oil cooler for cooling the hydraulic oil, and a cooling fan for feeding cooling air towards the heat exchangers.
In recent years it has become usual for construction machines such as hydraulic excavators to carry out operations at construction sites within towns and streets etc., and there has been a demand for low noise operation. A hydraulic excavator using a sirocco fan (multi-blade fan) that runs comparatively silently as a cooling fan to meet this requirement is disclosed, for example, in Utility Model Laid-open No. Hei. 6-1725 and Japanese Patent Laid-open No. Hei. 7-83054. With the hydraulic excavators in these publications, cooling air that has been sucked in by the sirocco fan is blown out to heat exchangers such as a radiator and an oil cooler arranged above the sirocco fan, and heat is exchanged between the cooling air and the cooling water inside the radiator, and the hydraulic oil inside the oil cooler.
With the hydraulic excavators described in the above publications, cooling air taken into an engine compartment is led to the heat exchangers by way of the outside of the engine. Thus, cooling air of comparatively high-temperature passes through the heat exchanger, and this is not preferable from the point of view of cooling efficiency. In order to achieve a specified heat balance, if the cooling efficiency is low, the rotational speed of the cooling fan must be increased or the heat exchangers must be made larger in size. However, if the rotational speed of the cooling fan is increased, it becomes noisier. Also, if the heat exchangers are made larger, the rear end radius of a machine body becomes larger and operation at narrow and limited construction sites such as are found within towns and streets becomes difficult.
The hydraulic excavators of the above publications have the heat exchangers mounted at an upper side of the sirocco fan, therefore the sirocco fan and the motor etc. become located at a position below the heat exchangers and become hidden from view. As a result, when carrying out inspection and maintenance of the sirocco fan and motor, such as cleaning and repair operations, there is a problem of poor operability because it is difficult for an operator's hands to reach the sirocco fan and motor, as well as the difficulty for visual confirmation.